(1) Field of the Invention
The present invention relates to an image reproducing device for reading an image from a recording medium and reproducing it upon each reception of reproduction request.
(2) Description of Related Art
An image reproducing device is preferably installed at a post production studio where edited images are stored in a hard disk or the like, while reproduced images are stored in tapes to be distributed to users such as a broadcasting station.
Such image reproducing device stores images into recording medium; however, recording medium is frequently damaged during transportation or storage. A partial image recorded in damaged part of recording medium cannot be reproduced; therefore, successive image reproduction is annoyed by unavoidable damage on recording medium.
This problem is described with a conventional image reproducing device.
FIG. 1 is a block diagram depicting the configuration of a conventional image reproducing device.
FIG. 2 shows an example of image recording medium which stores image information. The image recording medium in FIG. 2 includes image frames A, B, C, D, E, and F in which the frame D includes a faulty sector expressed by slash lines.
FIG. 3 shows an example of edit information stored in an edit information storing unit 1501. The edit information storing unit 1501 stores frame identifier, frame, and start address and end address indicating the start and the end of each frame. It is assumed that image information in FIG. 2 is read and reproduced. A reading controlling unit 1502 obtains information representing start address and end address of the frame A from the edit information storing unit 1501, and reads the frame A. The frame A can be read normally if no fault is included in itself stored in an image storing unit 1503, and it is sent to the an image reproducing unit 1504. Subsequently, the image reproducing unit 1504 sends the frame A to an image display unit 1505, and the image display unit 1505 displays image information of the frame A. Consequently, the frame A is reproduced. Similarly, the frames B and C are read and reproduced successively. After reading and reproducing the frame C, the reading control unit 1502 tries to read the frame D. However, the frame D cannot be read normally because of damage included in itself stored in the image storing unit 1503. The reading control unit 1502 judges that the frame D includes an faulty sector. Accordingly, as shown in FIG. 4, the reading control unit 1502 makes a substitution sector in a vacant area of the image storing unit 1503. Also, the reading control unit 1502 updates edit information stored in the edit information storing unit 1501 to read the substitution sector instead of the faulty sector.
FIG. 5 shows an example of updated edit information. The frame D in FIG. 4 is divided into three divisions D1, D2, D3; also a frame identifier 4 in FIG. 3 is divided into frame identifiers 7, 8, 9 in FIG. 5. Therefore, the reading controlling unit 1502 can read data successively by reading frames A, B, C, D1, D2, D3, E, and F in order according to the edit information in FIG. 5 which is stored in the edit information storing unit 1501.
However, this image reproducing device simply prepares a substitution sector with the reading controlling unit 1502 to overcome a faulty sector, and no image information is included in such substitution sector. As a result, reproduced image by the image reproducing unit 1504 includes an interruption for a moment, so that the original image cannot be reproduced.
Further, even if information at faulty sector is written into substitution sector, a reading head must migrate across sectors D1.fwdarw.D2.fwdarw.D3 within the time for reading one frame; therefore, successive reproduction is hardly possible. More specifically, migration of the reading head D1.fwdarw.D2 and D2.fwdarw.D3 requires seek time which consists of the time taken to rotate recording medium and the time taken to migrate the head to a certain track. In addition, generally a spare area for substitution sector is located at the most periphery or around the center of recording medium, so that the seek continues longer than expected, and it cannot be finished within the time limit set for reading a single frame. As a result, successive reproduction is hardly possible.